High pressure casting (die casting) is known as a method of obtaining, e.g., cast products of aluminum alloy. In the high pressure casting, the obtained cast products have excellent dimensional accuracy, and the high pressure casting enables mass production advantageously. Therefore, the high pressure casting method has been adopted widely.
In high pressure casting, molten metal poured into a plunger sleeve is extruded by a plunger tip, and the molten metal is supplied to a cavity. That is, an injection process is performed in the casting method.
In the process, the molten metal passes through a narrow runner and a gate, and is supplied into a cavity. In this case, for example, the molten metal staying in the gate may be solidified earlier than the molten metal which has reached the cavity. In such a situation, molten metal for a rise is not poured sufficiently. Therefore, this is one of factors which may cause occurrence of casting defects such as blow holes or cracks in the cast product.
In an attempt to avoid the occurrence of such defects, in a technique proposed in Japanese Laid-Open Patent Publication No. 07-001102, a pressurizing pin for applying pressure to molten metal in a cavity is provided. Further, vibrations are applied to the pressurizing pin from a vibration device such as a mechanical vibration generator or an ultrasonic vibrator.